This invention relates to a system for separating fluids from solids, drying these solids and in most cases, removing hydrocarbons remaining in the separated solids. More specifically, the invention relates to a drill cuttings disposal system for an oil well drilling operation involving two phases of operation that incorporates two separate units in which components in the first unit are operative in the first phase to separate solids from the fluid and components in the second unit are operative in the second phase to remove fluids remaining in the solids including use of a drying process.
Drilling operations are continually involved with the problem of disposing of drill solids sometimes referred to as cuttings. These cuttings always contain fluids and often contain hydrocarbons because of contact with formation oil and use of lubricating oils in the drilling operation. Federal regulations prevent discharge of the cuttings in waters in environmentally sensitive areas and in any controlled waters where the cuttings contain hydrocarbons in an amount that would cause an oil sheen on the water. State regulations are often more restrictive than federal rules and may completely preclude discharge of cuttings at the drill site. The problem of disposing of drill cuttings is further aggravated by the fact that it is anticipated that both federal and state regulations will become more stringent in the future.
Presently known systems include methods of separately washing cuttings in a detergent, steaming off a portion of the hydrocarbons, or heating the cuttings to remove a portion of hydrocarbons. These systems are usually bulky and consequently difficult to move to and mount at the drill site. They are also relatively inefficient and therefore expensive to operate. Most importantly, these systems are incapable of reducing hydrocarbon content by volume to an acceptable level permitting discharge of drill cuttings into surrounding waters. In sum, none of the presently known systems are both economically and technically feasible.
An obvious significant economical advantage of this invention is that it processes and drys cuttings at the drill site permitting easy disposal of the cuttings. Federal regulations permit offshore disposal of cuttings provided there is no discharge of free oil from the cuttings; that is, if a discharge does not cause a film or sheen upon or a discoloration on the surface of the water or adjoining shorelines or causes a sludge or emulsion to be deposited beneath the surface of the water or upon adjoining shorelines (40 C.F.R. Sub. 435.11(d)).
The present invention will reduce hydrocarbon levels in cuttings to comply with these federal standards. If more stringent state regulations are applicable then the invention will dry the cuttings making their handling and transportation to onshore disposal sites significantly easier and less expensive than under current methods of disposal. Similar principles are applicable for onshore drilling operations.